Breast Cancer
www.mayoclinic.com
It's not clear what causes breast cancer. Doctors know that breast cancer occurs when some breast cells begin growing abnormally. These cells divide
more rapidly than healthy cells do. The accumulating cells form a tumor that may spread (metastasize) through your breast, to your lymph nodes or to
other parts of your body.
Breast cancer most often begins with cells in the milk-producing ducts. Doctors call this type of breast cancer invasive ductal carcinoma. Breast cancer
may also begin in the milk glands known as lobules (invasive lobular carcinoma) within the breast.
Researchers have identified things that can increase your risk of breast cancer. But it's not clear why some people who have no risk factors develop
cancer, yet other people with risk factors never do. It's likely that breast cancer is caused by a complex interaction of your genetic makeup and your
environment.
Inherited breast cancer
Doctors estimate that only 5 to 10 percent of breast cancers are linked to gene mutations passed through generations of a family. A number of inherited
defective genes that can increase the likelihood of breast cancer have been identified. The most common are breast cancer gene 1 (BRCA1) and breast
cancer gene 2 (BRCA2), both of which increase the risk of both breast and ovarian cancer.
If you have a strong family history of breast cancer or other cancers, blood tests may help identify defective BRCA or other genes that are being passed
through your family. Consider asking your doctor for a referral to a genetic counselor, who can review your family health history. A genetic counselor can
also discuss the benefits, risks and limitations of genetic testing with you. It's important to remember that the genetic tests help to identify a high-risk
individual or family, but they don't definitively predict who will or will not get breast cancer.
Breast cancer prevention for women with an average risk
Making changes in your daily life may help reduce your risk of breast cancer. Try to:

Drink alcohol in moderation, if at all. Limit the amount of alcohol you drink to less than one drink a day, if you choose to drink.

Exercise most days of the week. Aim for at least 30 minutes of exercise on most days of the week. If you haven't been active lately, ask your doctor
whether it's OK and start slowly.

Limit postmenopausal hormone therapy. Combination hormone therapy may increase the risk of breast cancer. Talk with your doctor about the
benefits and risks of hormone therapy. Some women experience bothersome signs and symptoms during menopause and, for these women, the
increased risk of breast cancer may be acceptable in order to relieve menopause signs and symptoms. To reduce the risk of breast cancer, use the
lowest dose of hormone therapy possible for the shortest amount of time.

Maintain a healthy weight. If your current weight is healthy, work to maintain that weight. If you need to lose weight, ask your doctor about healthy
strategies to accomplish this. Reduce the number of calories you eat each day and slowly increase the amount of exercise.
Breast cancer prevention for women with a high risk
If your doctor has assessed your family history and other factors and determined that you may have an increased risk of breast cancer, options to
reduce your risk include:

Preventive medications (chemoprevention). Estrogen-blocking medications help reduce the risk of breast cancer. Options include tamoxifen and
raloxifene (Evista). These medications carry a risk of side effects, such as an increased risk of blood clots. Tamoxifen, but not raloxifene, is associated
with an increased risk of uterine cancer. So, it is important to talk to your doctors about your individual medical history to determine which medications
are right for you.

Preventive surgery. Women with a very high risk of breast cancer may choose to have their healthy breasts surgically removed (prophylactic
mastectomy). They may also choose to have their healthy ovaries removed (prophylactic oophorectomy) to reduce the risk of both breast cancer and
ovarian cancer.
Catch cancer early
Although you can't prevent the development of breast cancer with screening or breast self-exams, these techniques may help you and your doctor find
breast cancer in its earliest and more-treatable stages.

Ask your doctor about breast cancer screening. Ask your doctor at what age you should begin breast cancer screening exams and tests, such as
clinical breast exams and mammograms. Talk to your doctor about the benefits and risks of screening. Together you can decide what breast cancer
screening strategies are right for you.

Become familiar with your breasts through breast self-exams. Ask your doctor to show you how to do a breast self-exam to check for any lumps or
other unusual signs in your breasts. A breast self-exam can't prevent breast cancer, but it may help you to better understand the normal changes that
your breasts undergo and identify any unusual signs and symptoms.